Novel Application of Atomization Technology to a City Gas Calorific Value Adjustment System

Abstract

In Japan, the main feedstock for city gas is imported natural gas. In a city gas production process, the calorific value of natural gas is adjusted upward to regulated value of city gas by addition of LPG. In recent years, the method of adding LPG directly in the liquid phase has become the main stream in calorific value adjustment, where all of the added LPG must be securely vaporized. Otherwise, the LPG that does not contribute to increasing the calorific value flows out to the downstream side of the calorific value adjustment system, where the system is not functioning properly. Atomization of added LPG is the KEY for stable calorific value adjustment. In addition, demand for city gas varies greatly depending on the season and time of day, where a turndown, operating flow rate / rated flow rate, of natural gas reaches as small as 1/20, and that of LPG becomes even less than 1/500. The newly developed calorific value adjustment system realized complete and reliable atomization of added LPG over such a wide flow rate range without increasing pressure loss, resulting in a wide possible operating range and excellent calorific value controllability.